1. Field of the Invention
The present invention relates to the purification of solutions of gallium, and, more especially, to such purification as to obtain a solution of gallium chloride very high in purity.
The invention more particularly relates to a process for the purification of aqueous acid solutions of gallium, which process enabling obtainment of solutions of gallium having a degree of purity in excess of 99.99%.
2. Description of the Prior Art
The various applications of gallium in the field of electronics make it necessary to obtain the gallium in a very high degree of purity. It thus proves necessary to have available processes which enable, starting from solutions of gallium which do not meet the desired purity specifications, obtainment of solutions of gallium having a degree of purity in excess of 99.99%, from which solutions it will be possible to very readily obtain gallium oxide or gallium metal in the degrees of purity necessary for their various applications.
And indeed various processes have heretofore been proposed for separating gallium from other impurities, the most effective of which featuring the use of ion exchange resins.
However, the separation of gallium from certain metal ions, such as those of calcium, magnesium, aluminum, cobalt, vanadium, copper, manganese, sodium, zinc and, in particular, iron in the ferric state, proves inadequate when employing selective exchange of the gallium from the solution to be purified by means of an anion exchange resin [Chemical Abstracts, 55, 21974 IV (1961)]. To solve the problem of purification in the presence of iron in the ferric state, it too has been proposed [Chemical Abstracts, 55, 21974 V (1961), and 74, 108688 k (1971)] to reduce the iron to ferrous iron before percolating contact with the resin. Nonetheless, such a process is characterized by the fundamental disadvantage of not affording sufficient purification of the solution of gallium.